CVE-2021-46923

Kernel reference leak via failed path lookup

Published Feb 27, 2024 · Updated May 11, 2026

Resource leak in fs/namespace.c in Linux 5.12 through 5.15.12 allows local users to retain kernel references through mount_setattr. The function builds mount_kattr, including an ID-mapped mount reference, but returns after failed path lookup without calling finish_mount_kattr. Triggering the faulty error path requires CAP_SYS_ADMIN for an ID-mapped mount, and public records do not identify a direct data-access consequence.

CVSS severity5.5
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource leak in fs/namespace.c in Linux 5.12 through 5.15.12 allows local users to retain kernel references through mount_setattr. The function builds mount_kattr, including an ID-mapped mount reference, but returns after failed path lookup without calling finish_mount_kattr. Triggering the faulty error path requires CAP_SYS_ADMIN for an ID-mapped mount, and public records do not identify a direct data-access consequence.

The record

CVE
CVE-2021-46923
Published
Feb 27, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-668
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.12
  2. Affected versionversion=9caccd41541a6f7d6279928d9f971f6642c361af <012e332286e2bb9f6ac77d195f17e74b2963d663
  3. Affected versionversion=9caccd41541a6f7d6279928d9f971f6642c361af <47b5d0a7532d39e42a938f81e3904268145c341d

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=9caccd41541a6f7d6279928d9f971f6642c361af <012e332286e2bb9f6ac77d195f17e74b2963d663; version=9caccd41541a6f7d6279928d9f971f6642c361af <47b5d0a7532d39e42a938f81e3904268145c341d

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-668Exposure of Resource to Wrong Sphere

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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